Today is the Optional Memorial of St. Callistus, Pope and Martyr. Callistus was a Christian slave of Rome, and later was ordained deacon by Pope St. Zephyrinus, whom he succeeded as pope in the year 217. As deacon he was guardian of the Christian cemetery on the Appian Way which is still known by his name. While he vigorously opposed heresy, his charitable attitude toward repentant sinners incurred the wrath of contemporary rigorists. He was martyred in the persecutions of Alexander Severus in the year 223.